Mini screw driver

ABSTRACT

A small hand tool intended to be held in the fingers of one hand in which repetitive pushes on a plunger cause the turning of a substantially parallel drive shaft to which may be releasably attached various tool tips. A novel gear train is provided to (1) allow the drive shaft to be driven in either of two rotational directions, (2) allow the plunger to be returned to its initial position without simultaneously turning the drive shaft in a reverse direction, and (3) impart a large degree of rotary motion to the drive shaft in response to a relatively slight amount of reciprocating motion.

United States Patent Mella et al. 1 Sept. 4, 1973 [54] MINI SCREW DRIVER 1,597,025 8/1926 Eger 74/130 [75] Inventors: 232 8: :2? z i gg g Primary Examiner-Manuel A. Antonakas Assistant Examiner-Wesley S. Ratlifi, Jr. Assigneei Robert Mella, Santa Calif- Attorney-Allan R. Fowler, Gordon H. Olson et al.

[22] Flledz Oct. 4, 1971 ABSTRACT [21] PP N05 186,253 A small hand tool intended to be held in the fingers of one hand in which repetitive pushes on a plunger cause 52 us. c1 74/130, 81/5739, 145/70 the turning of a Substantially parallel drive shaft to 51 Int. Cl. Fl6h 27/02 which y be releasably attached various I001 p A 58 Field of Search 74/130; 81/5739, novel gear train is Provided to allow the drive Shaft 31/5746; 145/70, 76 to be driven in either of two rotational directions, (2) allow the plunger to be returned to its initial position [56] References Cited, without simultaneously turning the drive shaft in a re- UNITED STATES PATENTS verse direction, and (3) impart a large degree of rotary motion to the drive shaft in response to a relatively 1 513,82; 3%; Zigzag-lee 72/138 Slight amount of reciprocating motion. 2,510,978 6/1950 Hutton... 74/130 16 Claims, 4 Drawing Figures MINI SCREW DRIVER The present invention relates to small hand-held tools for importing rotary motion to tool tips such as are commonly, but not exclusively, used by jewelers, craftsmen and model makers in miniature assembly applications. Oftentimes, practitioners in these areas of endeavor encounter situations in which prior art devices are either impossible or particularly cumbersome or uncomfortable to use. To take but one example, a model-maker attempting to affix a small internal combustion engine to the cowl of a model airplane is faced with the task of screwing in a considerable number of tiny screws. This can be a time consuming and aggravating task using a traditional screwdriver. The present invention greatly reduces the time and trouble involved by providing a device wherein each stroke of the plunger of the device causes the screwdriver tip to rotate several times. The action is easier to accomplish than the turning of a small screwdriver in the usual fashion, and it is also less fatiguing to the operator because a relatively large amount of rotational motion is obtained for a small amount of reciprocal motion.

The foregoing example may be expanded to point out another advantage of the novel device. Assume additionally, as is generally the case with the installation of such model airplane engines as described above, that the space in which to use the screw driving device is especially confining, and it is therefore particularly difficult to manipulate a normal screwdriver. The present device can many times surmount this difficulty also since it is necessary only to reciprocate the plunger, normally with one s index finger (while holding the easing between ones thumb and middle finger), and thus the usual cumbersome twisting motion is eliminated. In close quarters the difference can be decisive.

Briefly described, the preferred embodiment of the present invention comprises a casing formed of upper and lower casing members, through which are passed, in parallel alignment, a plunger and a drive shaft, each extending from opposite ends of the apparatus. Gear means are provided within the casing for converting reciprocation of the plunger into rotation of the drive shaft. Attached to the lower end of the drive shaft are chuck means for removably retaining any of various tool tips. Mutual longitudinal sliding interaction of the two casing members between two detented positions is provided to change the gearing such that the drive shaft may be driven in either direction of rotation. Ratchet means are provided in the gear means to ensure that the drive shaft does not back off," that is, rotate in a reverse direction, when the plunger is returned to its initial, or up, position after each driving/or down, stroke. Hence, rotary motion is imparted to the drive shaft only on the down stroke of the plunger. The drive shaft does not rotate on the up stroke as the plunger is returning to its initial position. Chuck means are also provided for retaining, a variety of tool tips such that they will rotate with the drive shaft.

A more complete understanding of the unique advantages of the present invention may be obtained if reference be taken to the attached drawings, in which:

FIG. 1 is a perspective view of the preferred embodiment of the present invention;

FIG. 2 is a sectional view, taken along lines 22 of FIG. 1;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2; and

FIG. 4 is a cross-sectional view of the preferred embodiment taken along lines 4-4 of FIG. 2.

Referring first to FIG. 1, the mini screw driver of the present invention is shown to include a casing 10 comprised of an upper casing member 12 and a lower casing member 14, which in the preferred embodiment are generally cylindrical. (For purposes of explanation, the up direction will be assumed to be the left end of the device as shown in FIGS. 1 through 3; the down" direction will be to the right end.) A plunger 16 extends out the free end 18 of the upper casing member 12, and is provided at its tip with a cap 20 of such shape as to comfortably accommodate a human fingertip. Chuck means, shown here as a chuck 22 of a well known type, are shown with a screwdriver tip 24 engaged therein. The plunger 16 is adapted to reciprocate along its longitudinal axis, as will be described more fully below.

Turning now to the more detailed FIGS. 2, 3 and 4, there are shown the various elements of the gear means, which means are indicated generally by reference numeral 26. The upper casing member 12 is shown in the preferred embodiment to be formed of metal into a hollow cylindrical shape with one end (the free end 18) substantially closed. The inside surface of the upper casing member 12 is also cylindrical in shape. A hole 28 is provided in the free end 18 through which the plunger 16 may slidably pass. Bushing 30, inserted in the hole 28, ensures the proper axial alignment of the plunger 16 and reduces wear.

The lower casing member 14 comprises three integrally-formed metal portions. An upper portion 32 is of a substantially solid cylindrical shape. Through-holes 34 and 36 are provided, the axes of which parallel the longitudinal axis of the cylindrical upper portion 32 itself, to accommodate the plunger 16 and a drive shaft 38. The drive shaft 38 will be described below. A middle portion 40 is integrally formed with the upper portion 32, and extends longitudinally therefrom at the periphery of the lower end of the upper portion 32. The

middle portion 40 is of cut-down hollow cylindrical shape. Its outside circumferential portion aligns precisely with that of the upper portion 32. Formed integrally with the middle portion 40 is a lower portion 42 of the same solid cylindrical shape as the upper portion 32, but of substantially greater longitudinal extent. The longitudinal axis and diameter of the lower portion 42 are exactly those of the upper portion 32. The outermost dimension of the entire lower casing member 14 describes the form of a cylinder of such size as may snugly engage the inside of the upper casing member 12 in a slidable manner. The lower portion 42 is provided with longitudinally extending through-holes 44 and 46 in line with the holes 34 and 36 of the upper portion 32, to accommodate the plunger 16 and the drive shaft 38 such that the longitudinal axes of the plunger 16 and the drive shaft 38 are parallel. A slot 45 to accommodate the gear means 26 is provided in the middle portion 40.

When assembled, the lower casing member 14 is inserted into the upper casing member 12 until the upper end of the upper portion 32 of the lower casing member 14 is in close-spaced relationship with the free end 18 of the upper casing member 12 and the longitudinally extending holes 34 and 44 are in alignment with the hole 28 of the upper casing member 12. The gear means 26 are disposed generally inside the upper casing member 12 between the upper and lower portions 32 and 42, respectively, of the lower casing member 14. The axial position of the lower casing member 14 within the upper casing member 12 is controlled by de tent means, shown in the preferred embodiment as a ball-and-spring detent 47, which has only two positions, namely, those determined by the holes 47a and 47b in the upper casing member 12. The plunger 16, after assembly, extends through the three holes 28, 34 and 44, and is maintained in position by the bushings 30 (described above) and 48. The plunger 16 is thus maintained in position by mutual reciprocating engagement with both the upper casing member 12 and the lower casing member 14. The free end of the hole is capped in a well known fashion by a plug 50. A compression spring 52 is provided within the hole 44 to exert a force longitudinal of the plunger 16 when compressed.

The drive shaft 38 is disposed through the two aligned holes 36 and 46 of the lower casing member 14, in such a manner that it can rotate in either of the two possible directions of rotation about its longitudinal axis, namely, clockwise and counter-clockwise, as viewed in FIG. 4. It is maintained in proper axial alignment by bushings 54, 56, S8 and 60, and extends out the free end 61 of the lower casing member 14. The drive shaft 38 is maintained against axial movement by a snap-ring 62 in the preferred embodiment. The drive shaft 38 terminates at its lower end in chuck 22, which is attached to rotate therewith in the usual manner.

The gear means 26 mentioned above will now be described. Formed integrally with the plunger 16 is a rack 64. The rack 64 is disposed suitably to rotate by engagement therewith a spur gear 66 (to be described momentarily) when the plunger 16 is reciprocated. The spur gear 66 is maintained in position by a shaft 68 which is itself secured to a retaining member 70. The retaining member 70 is fixedly held in a substantially axially extending slot in the side of the upper casing member 12. Also maintained on the shaft 68, so as to turn with the spur gear 66, is a driving bevel gear 72. The axes of rotation of the spur gear 66 and the driving bevel gear 72 are collinear.

Retained on the drive shaft 38 immediately below the upper portion 32 of the lower casing member 14, with their axes of rotation parallel thereto, are two sets of driven bevel gears and ratchet gears, corresponding to the two directions of rotation of the drive shaft 38. Each set will be described separately.

An upper ratchet gear 74, slidably mounted on the drive shaft 38, is constrained to turn with the drive shaft 38 by means of a pin 76 passing through both the drive shaft 38 and an elongate hole 78 in the ratchet gear 74. An upper driven bevel gear 80 is provided to mesh with the ratchet gear 74. The driven bevel gear 80 is mounted such that it may rotate freely on the drive shaft 38 but not move longitudinally relative to the drive shaft. The axially elongate shape of the hole 78 allows the ratchet gear 74 to move axially along the drive shaft by a slight amount. The compression spring 82, however, biases the ratchet gear 74 toward the driving bevel gear 72. The ratchet gear 74 and bevel gear 80 are provided with teeth that mesh and rotate the ratchet gear when the bevel gear 80 is driven in one direction of rotation and permit the ratchet gear to slip, i.e., not rotate, when the bevel gear 80 is driven in the opposite direction. The function of the elongate hole 78 and the spring 82 in permitting this slippage will become apparent from the following discussion.

A second set of similar ratchet and driven bevel gears is retained in a complimentary manner on the drive shaft immediately above the lower portion 42 of the lower casing member 14. A lower ratchet gear 84 is retained as before by a pin 86 through the drive shaft 38 and an axially elongate hole 88. A lower driven bevel gear 90, freely mounted on the drive shaft 38, is provided to mesh with the lower ratchet gear 84. A compression spring 92 biases the lower ratchet gear 84 toward the driving bevel gear 72. The lower ratchet gear 84 is adapted to be driven in a direction of rotation opposite to that of the upper ratchet gear 74, and to slip when the bevel gear is driven in a direction opposite to that in which the upper ratchet gear 74 slips.

The upper and lower driven bevel gears and 90, respectively, are spaced apart from each other by a suitable distance, so that when the lower casing member 14 is in the position shown with respect to the upper casing member 12, that is, at what may be called the upper detented position, the driving bevel gear 72 engages the lower driven bevel gear 90. When the lower casing member 14 is at the lower detented position, the driving bevel gear 72 engages the upper driven bevel gear 80. This selective engagement of the driving bevel gear 72 with either of the two driven bevel gears 80 and 90, by translating the upper casing member 12 longitudinally of the lower casing member 14, constitutes a means for adjustably selecting either direction of rotation of the drive shaft 38.

To describe the operation of the preferred embodiment of the present invention, it will be assumed first that the mini screw driver is at the upper detented position, as shown in FIGS. 2 and 3, and that a screwdriver tip 24 is retained in the chuck 22. An operator grasps the device between the thumb and middle finger of one hand and applies the tip 24 to the head of a screw. Upon pressing the plunger with the index finger of the same hand, the gear means 26 will cause the tip 24 to rotate in a counter-clockwise direction, such as would remove a standard right-hand screw. The tip 24 will rotate a specific number of times for each down stroke of the plunger. (It has been found advantageous to provide three revolutions of the drive shaft 38 per each down stroke.) When the operator releases the pressure on the plunger, the spring 52 forces it upward until it resumes its initial position at which time it is ready for another down stroke.

Much of the importance and usefulness of the ratchet means lies in its preventing the screwdriver tip 24 from being reversed, i.e., backed off, on the up stroke of the plunger 16. Assuming the plunger 16 is in the down position and is starting to move upwardly under the urging of the spring 52, it can be seen that the lower driven bevel gear will be rotated along with the driving bevel gear 72. The spring 82 and the elongate hole 88 allow the lower ratchet gear 84 to slip on the lower driven bevel gear 90 rather than rotate with it. In other words, the lower driven bevel gear 90 cannot move axially along the drive shaft 38 so as to slip on the teeth of the lower ratchet gear 84. Thus, the axial traverse necessary to accomplish the slipping disengagement between the lower driven bevel gear 90 and the lower ratchet gear 84 must be made by the lower ratchet gear 84. This it does by moving against the tension of the spring 82.

Assume now that an operator desires to drive a screw into a hole with the mini screw driver of the present invention. The upper casing member 12 is translated axially with respect to the lower casing member 14 to the lower detented position. When the mini screw driver is in the lower detented position, the driving bevel gear 72 will engage the upper driven bevel gear 80. The screwdriver tip 24 will be caused to rotate in a clockwise direction when the plunger 16 is depressed, such as is suitable to drive a right-hand screw into a hole. Upon releasing pressure upon the plunger 16, the upper ratchet means will allow the plunger 16 to be pushed upwardly by the spring without causing the tip 24 to be simultaneously rotated in a counter-clockwise direction. Thus, the plunger 16 is allowed to return to its initial position by the selective shipping interaction of the upper and lower driven bevel gears 80, 90 with the upper and lower ratchet gears 74, 84, respectively.

It is also contemplated that the device of the present invention be used with other types of tool tips, e.g., socket wrenches, drills, taps, and dies, which require a rotary motion and which could be held in the chuck or formed at the end of the drive shaft 38.

What is claimed is:

1. A hand tool for imparting rotary motion to a tool tip, comprising:

a tool body, constructed in a size and shape to allow the body to be conveniently held and manipulated in one hand of an operator;

a plunger, having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis relative said tool body, said plunger oriented relative said tool body to allow reciprocation thereof with said one hand of said operator while said tool body is manipulated with said one hand;

a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel;

gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft;

a tool tip connected to the drive shaft for rotation therewith; and

means for selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft in response to reciprocation of said plunger.

2. The apparatus set forth in claim 1 additionally comprising means for allowing said plunger to return to its initial position without reversing said drive shaft.

3. A hand tool for imparting rotary motion to a tool tip, comprising:

a plunger, having a rack found integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis;

a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel;

gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft;

a tool tip connected to the drive shaft for rotation therewith; and

means for allowing said plunger to return to its initial position without reversing said drive shaft, comprising: first and second driven bevel gears mounted to rotate freely on said drive shaft; a driving bevel gear for rotating said first and second driven bevel gears;

first and second ratchet gears mounted on said drive shaft and constrained to rotate therewith; and

means for selectively operatively connecting said first or second ratchet gear with said driving bevel gear through said first or second driven bevel gear, respectively, such that when said driving bevel gear is connected through said first driven bevel gear, said first driven bevel gear will mesh with said first ratchet gear when said plunger is moving downwardly to rotate said drive shaft in a first direction, and will slip with respect to said first ratchet gear when said plunger is moving upwardly; and when said driving bevel gear is connected through said second driven bevel gear, said second driven bevel gear will mesh with said second ratchet gear when said plunger is moving downwardly and thus rotate said drive shaft in the opposite direction and will slip with respect to said second ratchet gear gear when said plunger is moving upwardly.

4. A hand tool for imparting rotary motion to a tool tip, comprising:

a plunger, having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis;

a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel;

gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft;

a tool tip connected to the drive shaft for rotation therewith; and

means for selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft, comprising:

a driving bevel gear;

two driven bevel gears each for causing rotation of the drive shaft in an opposite direction; and

means for selectively operatively connecting the driving bevel gear with the drive shaft through a selected one of the two driven bevel gears.

5. The apparatus set forth in claim 4 in which said means for selectively operatively connecting the driving bevel gear with the drive shaft is responsive to translating an upper casing half, to which said driving bevel gear is rotatably attached, longitudinally of a lower casing half.

6. A hand tool for imparting rotary motion to a tool tip, comprising a plunger having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinaLaxis, a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel, gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft, and a tool tip connected to the drive shaft for rotation therewith, in which said gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft comprises:

a spur gear engaged with said rack and adapted to be rotated thereby when said plunger is reciprocated;

a driving bevel gear fixed to rotate with said spur gear;

a driven bevel gear mounted on said drive shaft and adapted to rotate about said longitudinal axis thereof, said driven bevel gear being rotated through engagement with said driving bevel gear;

and

means for converting the rotation of said driven bevel gear to rotation of said drive shaft.

7. The apparatus set forth in claim 6 wherein the driven bevel gear is free to rotate on the drive shaft and the means for converting the rotation of said driven bevel gear to rotation of said drive shaft comprise:

a ratchet gear mounted on said drive shaft and constrained to rotate therewith; and

means for meshing said ratchet gear with said driven bevel gear when said driven bevel gear is rotated in a first direction of rotation about said longitudinal axis of said drive shaft by said driving bevel gear, to rotate said drive shaft in said first direction, and for permitting slippage of said ratchet gear relative to said driven bevel gear when said driven bevel gear is rotated in a second direction of rotation about said longitudinal axis of said drive shaft, thus imparting no rotation to said drive shaft.

8. A hand tool for imparting rotary motion to a tool tip, comprising:

a plunger, having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis;

a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel;

gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft, comprising:

a spur gear adapted to be rotated through engagement with said rack when said plunger is reciprocated;

first and second driven bevel gears adapted to rotate freely on said drive shaft, the axes of roation of which are collinear with said longitudinal axis of said drive shaft;

a driving bevel gear fixedly mounted with said spur gear, with the axes of rotation of said driving bevel gear and said spur gear collinear;

means for selectively engaging said first or second driven bevel gears with said driving bevel gear so as to rotate said first or second driven bevel gears when selectively engaged therewith, the direction of rotation being opposite depending on which driven bevel gear is engaged; and

first and second ratchet gears, mounted on said drive shaft in spaced-apart manner and constrained to rotate therewith; said first ratchet gear being adapted to mesh with said first driven bevel gear when said first driven bevel gear is driven in one direction of rotation by said driving bevel gear, thus to rotate said drive shaft in said one direction of rotation, and to slip when said first driven bevel gear is driven in the other direction of rotation by said driving bevel gear; said second ratchet gear being adapted to mesh with said second driven bevel gear when said second driven bevel gear is driven in said other direction of rotation by said driving bevel gear, thus to rotate said drive shaft in said other direction of rotation, and to slip when said second driven bevel gear is driven in said one direction of rotation by said driving bevel gear; and

a tool tip connected to the drive shaft for rotation therewith.

9. The apparatus set forth in claim 8 wherein said means for selectively engaging said first or second driven bevel gear with said driving bevel gear comprises:

first and second casing members connected to permit relative longitudinal shifting;

means mounting said driving bevel gear on said first casing member for shifting therewith;

means mounting said drive shaft and driven bevel l0 gear on said second casing member for shifting therewith; and

means for selectively and releasably retaining said two casing members in a first position with the driving bevel gear and first driven bevel gear engaged,

or in a second position with the driving bevel gear and second driven bevel gear engaged.

10. A hand tool for imparting rotary motion to a tool tip, comprising:

a plunger, having a rack formed integrally therewith, said plunger being adapted to reciprocate parallel to its longitudinal axis;

a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel;

gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft;

means for allowing said plunger to return to its initial position without reversing the direction of rotation of said drive-shaft thereby, comprising:

first and second driven bevel gears mounted to rotate freely on said drive shaft;

a driving bevel gear adapted to be selectively engaged with said first and second driven bevel gears; and

first and second ratchet gears mounted on said drive shaft and constrained to rotate therewith, and adapted to be selectively engaged with said first and second driven bevel gears, respectively, and further adapted such that: when said driving bevel gear is in engagement with said first driven bevel gear, said first driven bevel gear will mesh with said first ratchet gear when said plunger is moving downwardly and thus turn said drive shaft in one of the two possible directions of rotation about said longitudinal axis of said drive shaft, and slip with respect to said first ratchet gear when said plunger is moving upwardly; and when said driving bevel gear is in engagement with said second driven bevel gear, said second driven bevel gear will mesh with said second ratchet gear when said plunger is moving downwardly and thus turn said drive shaft in the other of two possible directions of rotation about said longitudinal axis of said drive shaft, and slip with respect to said second ratchet gear when said plunger is moving upwardly;

means for adjustably selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft; and

chuck means for retaining said tool tip such that said tool tip rotates with said drive shaft.

11. A hand tool for use with a variety of tool tips,

comprising:

first and second casing members adapted such that said second casing member may slide axially within said first casing member adjustably to either of two detented positions, said first and second casing members having parallel longitudinal axes;

a plunger maintained substantially parallel to the longitudinal axes of said first and second casing members by mutual reciprocating engagement with both of said casing members, said plunger extending out the free end of said first casing portion;

a drive shaft maintained substantially parallel to the longitudinal axes of said first and second casing members by engagement therewith, said drive shaft being mounted for rotation about its longitudinal axis, and extending out the free end of said second casing member;

rack means formed integrally with said plunger along a substantial portion of the length thereof;

gear means for engagement with said rack means of said plunger for the purpose of converting the reciprocating motion of said plunger to rotary motion of said drive shaft;

means responsive to selection of one of said two detented positions of the casing members for causing said gear means to rotate the drive shaft in a first direction and responsive to selection of the other detented position for causing the gear means to rotate the drive shaft in the opposite direction; and

a tool tip attached to said drive shaft.

12. A hand tool for imparting rotary motion to a tool tip, comprising:

a rack;

a plunger for reciprocating said rack;

a spur gear adapted to be rotated by interaction with said rack;

a driving bevel gear fixedly attached to said spur gear, and with the axes of rotation collinear so as to rotate with said spur gear;

a drive shaft extending parallel to said plunger;

first and second ratchet gears disposed in spacedapart relationship on said drive shaft;

first and second driven bevel gears disposed on said drive shaft and engaged with said first and second ratchet gears, respectively, the interconnection therebetween being such that said drive shaft is rotated in one direction when said driving bevel gear is engaged with said first driven bevel gear, and said drive shaft is rotated in an opposite direction when said driving bevel gear is engaged with said second driven bevel gear; and

chuck means at the free end of said drive shaft for attaching a plurality of tools to said hand tool such that they will be rotated by the drive shaft.

13. A hand tool for imparting rotary motion to a tool tip, comprising:

a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel;

gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft;

a tool tip connected to the drive shaft for rotation I therewith; and

means for selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft, which comprises:

a driving gear;

two driven gears, spaced longitudinally with respect to the drive shaft, engagement of said gears respectively causing rotation of said drive shaft in opposite directions; and

means for selectively engaging said driving gear with said drive shaft through a selected one of said two driven gears through a longitudinal shifting of said driving gear relative to said driven gear.

14. In a hand tool for imparting rotary motion to a tool tip, which hand tool comprises a reciprocable plunger with a rack affixed to move therewith, a drive shaft parallel to said plunger, means for converting reciprocation of said plunger to rotation of said drive shaft, and a tool tip for rotation with said driven shaft, means for selecting the direction of rotation of said drive shaft, comprising:

first gear means comprising two longitudinally spaced gears;

second gear means for engaging said first gear means, one of said first and second gear means being driven gear means and the other of said first and second gear means being driving gear means; and

means for longitudinally shifting said first and second gear means relative to each other between a first and a second position, so that when said first and second gear means are in said first position, one of said gears of said first gear means is engaged with said second gear means, and and when said first and second gear means are in said second position, the other of said gears of said first gear means is engaged with said second gear means.

15. The hand tool as defined in claim 14, in which said first gear means is said driving gear means, and in which said gears of said first gear means comprise spur gears in engagement with said rack.

16. The hand tool as defined in claim 14, in which:

said first gear means is said driven gear means, and said first gear means comprises two longitudinally spaced spur gears; and

said second gear means comprises a spur gear engaged with said rack. 

1. A hand tool for imparting rotary motion to a tool tip, comprising: a tool body, constructed in a size and shape to allow the body to be conveniently held and manipulated in one hand of an operator; a plunger, having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis relative said tool body, said plunger oriented relative said tool body to allow reciprocation thereof with said one hand of said operator while said tool body is manipulated with said one hand; a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel; gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft; a tool tip connected to the drive shaft for rotation therewith; and means for selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft in response to reciprocation of said plunger.
 2. The apparatus set forth in claim 1 additionally comprising means for allowing said plunger to return to its initial position without reversing said drive shaft.
 3. A hand tool for imparting rotary motion to a tool tip, comprising: a plunger, having a rack found integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis; a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel; gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft; a tool tip connected to the drive shaft for rotation therewith; and means for allowing said plunger to return to its initial position without reversing said drive shaft, comprising: first and second driven bevel gears mounted to rotate freely on said drive shaft; a driving bevel gear for rotating said first and second driven bevel gears; first and second ratchet gears mounted on said drive shaft and constrained to rotate therewith; and means for selectively operatively connecting said first or second ratchet gear with said driving bevel gear through said first or second driven bevel gear, respectively, such that when said driving bevel gear is connected through said first driven bevel gear, said first driven bevel gear will mesh with said first ratchet gear when said plunger is moving downwardly to rotate said drive shaft in a first direction, and will slip with respect to said first ratchet gear when said plunger is moving upwardly; and when said driving bevel gear is connected through said second driven bevel gear, said second driven bevel gear will mesh with said second ratchet gear when said plunger is moving downwardly and thus rotate said drive shaft in the opposite direction and will slip with respect to said second ratchet gear gear when said plunger is moving upwardly.
 4. A hand tool for imparting rotary motion to a tool tip, comprising: a plunger, having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis; a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel; gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft; a tool tip connected to the drive shaft for rotation therewith; and means for selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft, Comprising: a driving bevel gear; two driven bevel gears each for causing rotation of the drive shaft in an opposite direction; and means for selectively operatively connecting the driving bevel gear with the drive shaft through a selected one of the two driven bevel gears.
 5. The apparatus set forth in claim 4 in which said means for selectively operatively connecting the driving bevel gear with the drive shaft is responsive to translating an upper casing half, to which said driving bevel gear is rotatably attached, longitudinally of a lower casing half.
 6. A hand tool for imparting rotary motion to a tool tip, comprising a plunger having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis, a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel, gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft, and a tool tip connected to the drive shaft for rotation therewith, in which said gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft comprises: a spur gear engaged with said rack and adapted to be rotated thereby when said plunger is reciprocated; a driving bevel gear fixed to rotate with said spur gear; a driven bevel gear mounted on said drive shaft and adapted to rotate about said longitudinal axis thereof, said driven bevel gear being rotated through engagement with said driving bevel gear; and means for converting the rotation of said driven bevel gear to rotation of said drive shaft.
 7. The apparatus set forth in claim 6 wherein the driven bevel gear is free to rotate on the drive shaft and the means for converting the rotation of said driven bevel gear to rotation of said drive shaft comprise: a ratchet gear mounted on said drive shaft and constrained to rotate therewith; and means for meshing said ratchet gear with said driven bevel gear when said driven bevel gear is rotated in a first direction of rotation about said longitudinal axis of said drive shaft by said driving bevel gear, to rotate said drive shaft in said first direction, and for permitting slippage of said ratchet gear relative to said driven bevel gear when said driven bevel gear is rotated in a second direction of rotation about said longitudinal axis of said drive shaft, thus imparting no rotation to said drive shaft.
 8. A hand tool for imparting rotary motion to a tool tip, comprising: a plunger, having a rack formed integrally therewith, which plunger is adapted to reciprocate along its longitudinal axis; a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel; gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft, comprising: a spur gear adapted to be rotated through engagement with said rack when said plunger is reciprocated; first and second driven bevel gears adapted to rotate freely on said drive shaft, the axes of roation of which are collinear with said longitudinal axis of said drive shaft; a driving bevel gear fixedly mounted with said spur gear, with the axes of rotation of said driving bevel gear and said spur gear collinear; means for selectively engaging said first or second driven bevel gears with said driving bevel gear so as to rotate said first or second driven bevel gears when selectively engaged therewith, the direction of rotation being opposite depending on which driven bevel gear is engaged; and first and second ratchet gears, mounted on said drive shaft in spaced-apart manner and constrained to rotate therewith; said first ratchet gear being adapted to mesh with said first driven bevel gear when said first driven bevel gear is driven in one direction of rotation by said driving bevel gear, thus to rotate said drive shaft in said one direction of rotation, and tO slip when said first driven bevel gear is driven in the other direction of rotation by said driving bevel gear; said second ratchet gear being adapted to mesh with said second driven bevel gear when said second driven bevel gear is driven in said other direction of rotation by said driving bevel gear, thus to rotate said drive shaft in said other direction of rotation, and to slip when said second driven bevel gear is driven in said one direction of rotation by said driving bevel gear; and a tool tip connected to the drive shaft for rotation therewith.
 9. The apparatus set forth in claim 8 wherein said means for selectively engaging said first or second driven bevel gear with said driving bevel gear comprises: first and second casing members connected to permit relative longitudinal shifting; means mounting said driving bevel gear on said first casing member for shifting therewith; means mounting said drive shaft and driven bevel gear on said second casing member for shifting therewith; and means for selectively and releasably retaining said two casing members in a first position with the driving bevel gear and first driven bevel gear engaged, or in a second position with the driving bevel gear and second driven bevel gear engaged.
 10. A hand tool for imparting rotary motion to a tool tip, comprising: a plunger, having a rack formed integrally therewith, said plunger being adapted to reciprocate parallel to its longitudinal axis; a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel; gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft; means for allowing said plunger to return to its initial position without reversing the direction of rotation of said drive shaft thereby, comprising: first and second driven bevel gears mounted to rotate freely on said drive shaft; a driving bevel gear adapted to be selectively engaged with said first and second driven bevel gears; and first and second ratchet gears mounted on said drive shaft and constrained to rotate therewith, and adapted to be selectively engaged with said first and second driven bevel gears, respectively, and further adapted such that: when said driving bevel gear is in engagement with said first driven bevel gear, said first driven bevel gear will mesh with said first ratchet gear when said plunger is moving downwardly and thus turn said drive shaft in one of the two possible directions of rotation about said longitudinal axis of said drive shaft, and slip with respect to said first ratchet gear when said plunger is moving upwardly; and when said driving bevel gear is in engagement with said second driven bevel gear, said second driven bevel gear will mesh with said second ratchet gear when said plunger is moving downwardly and thus turn said drive shaft in the other of two possible directions of rotation about said longitudinal axis of said drive shaft, and slip with respect to said second ratchet gear when said plunger is moving upwardly; means for adjustably selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft; and chuck means for retaining said tool tip such that said tool tip rotates with said drive shaft.
 11. A hand tool for use with a variety of tool tips, comprising: first and second casing members adapted such that said second casing member may slide axially within said first casing member adjustably to either of two detented positions, said first and second casing members having parallel longitudinal axes; a plunger maintained substantially parallel to the longitudinal axes of said first and second casing members by mutual reciprocating engagement with both of said casing members, said plunger extending out the free end of said first casing portion; a drive shaft maintained substantially parallel to the longitudinal axes of said first aNd second casing members by engagement therewith, said drive shaft being mounted for rotation about its longitudinal axis, and extending out the free end of said second casing member; rack means formed integrally with said plunger along a substantial portion of the length thereof; gear means for engagement with said rack means of said plunger for the purpose of converting the reciprocating motion of said plunger to rotary motion of said drive shaft; means responsive to selection of one of said two detented positions of the casing members for causing said gear means to rotate the drive shaft in a first direction and responsive to selection of the other detented position for causing the gear means to rotate the drive shaft in the opposite direction; and a tool tip attached to said drive shaft.
 12. A hand tool for imparting rotary motion to a tool tip, comprising: a rack; a plunger for reciprocating said rack; a spur gear adapted to be rotated by interaction with said rack; a driving bevel gear fixedly attached to said spur gear, and with the axes of rotation collinear so as to rotate with said spur gear; a drive shaft extending parallel to said plunger; first and second ratchet gears disposed in spaced-apart relationship on said drive shaft; first and second driven bevel gears disposed on said drive shaft and engaged with said first and second ratchet gears, respectively, the interconnection therebetween being such that said drive shaft is rotated in one direction when said driving bevel gear is engaged with said first driven bevel gear, and said drive shaft is rotated in an opposite direction when said driving bevel gear is engaged with said second driven bevel gear; and chuck means at the free end of said drive shaft for attaching a plurality of tools to said hand tool such that they will be rotated by the drive shaft.
 13. A hand tool for imparting rotary motion to a tool tip, comprising: a plunger, having a rack affixed to move therewith, which plunger is adapted to reciprocate along its longitudinal axis; a drive shaft disposed such that the longitudinal axes of said plunger and said drive shaft are substantially parallel; gear means for converting the reciprocating motion of said rack to rotary motion of said drive shaft; a tool tip connected to the drive shaft for rotation therewith; and means for selecting either direction of rotation of said drive shaft about said longitudinal axis of said drive shaft, which comprises: a driving gear; two driven gears, spaced longitudinally with respect to the drive shaft, engagement of said gears respectively causing rotation of said drive shaft in opposite directions; and means for selectively engaging said driving gear with said drive shaft through a selected one of said two driven gears through a longitudinal shifting of said driving gear relative to said driven gear.
 14. In a hand tool for imparting rotary motion to a tool tip, which hand tool comprises a reciprocable plunger with a rack affixed to move therewith, a drive shaft parallel to said plunger, means for converting reciprocation of said plunger to rotation of said drive shaft, and a tool tip for rotation with said driven shaft, means for selecting the direction of rotation of said drive shaft, comprising: first gear means comprising two longitudinally spaced gears; second gear means for engaging said first gear means, one of said first and second gear means being driven gear means and the other of said first and second gear means being driving gear means; and means for longitudinally shifting said first and second gear means relative to each other between a first and a second position, so that when said first and second gear means are in said first position, one of said gears of said first gear means is engaged with said second gear means, and and when said first and second gear means are in said second position, the other of said gears of said first gear means is engaged with said second gear means.
 15. The hand tool as defined in claim 14, in which said first gear means is said driving gear means, and in which said gears of said first gear means comprise spur gears in engagement with said rack.
 16. The hand tool as defined in claim 14, in which: said first gear means is said driven gear means, and said first gear means comprises two longitudinally spaced spur gears; and said second gear means comprises a spur gear engaged with said rack. 